How to take one half of a stereo file and make it mono?

This one is a bit weird. So, I did an edit to a stereo mix, which happened to be in the form of two mono files. (They end up back on my outboard digital recorder that way, so it made sense to keep them in two mono files.) Anyway, to save the edit in two files, I 'glued items' for each mono track. first the L channel and then the R channel. Reaper saved these two glued mono files as two sets of stereo tracks. Confirmed by their waveform and how much data they take up. I just want two mono files. The edit: 1. Took a long time 2. Was perfect 3. Was lost Is there a way I can make these two sets of stereo left and stereo right channels into simply two mono files? And not undermine the quality of the mix in any way? What's the cleanest way to do this?

Media item properties -> Channel mode, set to mono (choose left or right, whatever you need). Then glue or render out. Alternatively, if you're on Windows, download Wavosaure (it's free), and you can strip unnecessary channels there and save changes, without the need to re-render.

Sorry, I misread your post the first time. You're giving me the directions to "glue" again and get what I want. So, it's not going to sum the stereo tracks together? It'll just take one side of the stereo file? That's what I want.

I think that item channel mode does apply to glue, yes.

What Evildragon said. I think you want two separate mono files split from the left and right of a stereo file, right? So . . . load into Reaper, right click on the WAV, go to 'item properties', and in channel mode select either left or right. Render this as a mono file. Right click again on the WAV, and this time select the other channel. Render this as a mono file (give it a different name). That gives you two mono files, one being the left channel of the stereo file, the other being the right channel.

Maybe I'm missing the point, but it seems that the easiest solution would be to right-click on the media item and select Item Processing -> Explode multichannel audio or MIDI items to new one-channel items. I just did that on a stereo track and it created two mono tracks. Apologies if I'm answering a different question than the one being asked.